to sort out
- https://en.wikipedia.org/wiki/Sleep_architecture - describes the structure and pattern of sleep and encompasses several variables.
- https://en.wikipedia.org/wiki/Hypnagogia - also referred to as "hypnagogic hallucinations", is the experience of the transitional state from wakefulness to sleep: the hypnagogic state of consciousness, during the onset of sleep. (For the transitional state from sleep to wakefulness see hypnopompic.) Mental phenomena that may occur during this "threshold consciousness" phase include lucid thought, lucid dreaming, hallucinations and, sleep paralysis. However, sleep paralysis and lucid dreaming are separate sleep conditions that are sometimes experienced during the hypnagogic state.
- https://en.wikipedia.org/wiki/Hypnic_jerk - hypnagogic jerk, sleep start, sleep twitch or night start is an involuntary twitch which occurs when a person is beginning to fall asleep, often causing them to awaken suddenly for a moment. Physically, hypnic jerks resemble the "jump" experienced by a person when startled, sometimes accompanied by a falling sensation. Hypnic jerks are associated with a rapid heartbeat, quickened breathing, sweat, and sometimes "a peculiar sensory feeling of 'shock' or 'falling into the void'". A higher occurrence is reported in people with irregular sleep schedules.
- https://en.wikipedia.org/wiki/Somnolence - alternatively "sleepiness" or "drowsiness", is a state of near-sleep, a strong desire for sleep, or sleeping for unusually long periods (cf. hypersomnia). It has two distinct meanings, referring both to the usual state preceding falling asleep, and the chronic condition referring to being in that state independent of a circadian rhythm. "Somnolence" is derived from the Latin "somnus" meaning "sleep."
- http://www.nytimes.com/2012/09/23/opinion/sunday/rethinking-sleep.html 
- http://dealbook.nytimes.com/2014/06/27/sleep-as-a-competitive-advantage/  - "The research is overwhelming that the vast majority of us require seven to eight hours of sleep to feel fully rested, and only a small percentage require less than seven."
The technique is said to work for 96 per cent of people after six weeks of practice. Here’s how to do it:
- Relax the muscles in your face, including tongue, jaw and the muscles around the eyes
- Drop your shoulders as far down as they’ll go, followed by your upper and lower arm, one side at a time
- Breathe out, relaxing your chest followed by your legs, starting from the thighs and working down
- You should then spend 10 seconds trying to clear your mind before thinking about one of the three following images:
- You’re lying in a canoe on a calm lake with nothing but a clear blue sky above you
- You’re lying in a black velvet hammock in a pitch-black room
- You say “don’t think, don’t think, don’t think” to yourself over and over for about 10 seconds.
- f.luxometer - measure light spectra with a portable meter and see circadian quantities like melanopic lux and M/P ratio instantly. Save the raw data and analyze it however you like. Or, when you want to, share your results online, in just one click.